SOLUTION: At a thrift store, each shirt costs $4, each pair of pants costs $7, and there is no sales tax on clothing purchases. Jason bought some shirts and some pairs of pants at the thrift
Question 1109749: At a thrift store, each shirt costs $4, each pair of pants costs $7, and there is no sales tax on clothing purchases. Jason bought some shirts and some pairs of pants at the thrift store and paid exactly $41. How many shirts and how many pairs of pants did Jason buy at the thrift store?
If x is the number of shirts and y is the number of pairs of pants, then
You can solve this using formal algebra and the fact that x and y have to be whole numbers. However, since the numbers are small, it is much faster to solve the problem by logical reasoning and a bit of trial and error.
You know the total spent is an odd number; the cost of a shirt is an even number and the cost of a pair of pants is an odd number. Logic tells you then that the number of pairs of pants must be odd. So
1 pair of pants = $7; $41-$7 = $34; but 34 is not divisible by 4.